Dear Robert,

many thanks for the answer, but in my case I used an in vitro models of intestinal fermentation without delivery system. Are independent vessels (each with a different substrate, but the same basal medium) with water circulation for maintaining the temperature at 37°C, pH controller with acid and basic solutions to maintain the pH in the predetermined range and N2 gas flow for have an anaerobic environment.

My first experiment was set to last 36 hours, perhaps beyond the capabilities of the system. I would like to study the metabolism of a set of amino acids.

I would be grateful for any suggestions.